Field
The teachings in accordance with the exemplary embodiments of this present disclosure generally relate to an apparatus and method for restarting a medium voltage inverter.
Background
In general, a multilevel medium voltage inverter means an inverter having an input power whose rms (root mean square) value is over 600V for a line-to-line voltage, and has several stages in output phase voltage. The multilevel medium voltage inverter is generally used to drive a large capacity motor ranging from several kW to several MW capacities.
A medium voltage motor driven by a medium voltage inverter generally has a large inertia, such that a rotor speed of the medium voltage motor hardly decreases to a great extent, even if an inverter unit of the medium voltage inverter fails to perform a normal operation due to instantaneous failure or instantaneous blackout of input power. Owning to this reason, the medium voltage motor must be re-started after waiting until the rotor speed reaches zero speed when the input power is returned from failure to a normal state.